The prevalence and relevance of the Brugada-type electrocardiogram in the Danish general population: data from the Copenhagen City Heart Study

Defining electrocardiographic criteria to differentiate non-type 1 Brugada ECG variants from normal incomplete RBBB patterns in the young SCD-SOS cohort

INTRODUCTION

We assessed the prevalence of non-type 1 Brugada pattern (T1BrP) in children and young adults from the Sudden Cardiac Death-Screening Of risk factorS cohort and the diagnostic yield of nonexpert manual and automatic algorithm electrocardiogram (ECG) measurements.

METHODS

Cross-sectional study. We reviewed 14 662 ECGs and identified 2226 with a rSr'-pattern in V1-V2. Among these, 115 were classified by experts in hereditary arrhythmic-syndromes as having or not non-T1BrP, and were compared with measurements of 5 ECG-derived parameters based on a triangle formed by r' -wave (d(A), d(B), d(B)/h, β-angle) and ST-ascent, assessed both automatically and manually by nonexperts. We estimated intra- and interobserver concordance for each criterion, calculated diagnostic accuracy and defined the most appropriate cut-off values.

RESULTS

A rSr'-pattern in V1-V2 was associated with higher PQ interval and QRS duration, male gender, and lower body mass index (BMI). The manual measurements of non-T1BrP criteria were moderately reproducible with high intraobserver and moderate interobserver concordance coefficients (ICC: 0.72-0.98, and 0.63-0.76). Criteria with higher discriminatory capacity were: distance d(B) (0.72; 95% confidence interval [CI]: 0.65-0.80) and ST-ascent (0.87; 95% CI: 0.82-0.92), which was superior to the 4 r'-wave criteria together (area under curve [AUC: 0.74]). We suggest new cut-offs with improved combination of sensitivity and specificity: d(B) ≥ 1.4 mm and ST-ascent ≥ 0.7 mm (sensitivity: 1%-82%; specificity: 71%-84%), that can be automatically measured to allow classification in four morphologies with increasing non-T1BrP probability.

CONCLUSION

rSr'-pattern in precordial leads V1-V2 is a frequent finding and the detection of non-T1BrP by using the aforementioned five measurements is reproducible and accurate. In this study, we describe new cut-off values that may help untrained clinicians to identify young individuals who may require further work-up for a potential Brugada Syndrome diagnosis.

Brugada syndrome: should we be screening patients before prescribing psychotropic medication?

Brugada syndrome (BrS) presents with a characteristic electrocardiogram (ECG) and is associated with sudden cardiac death. Until now, prolongation of QTc interval and its association with Torsade de Pointe and possible fatal arrhythmia have been the focus of routine baseline ECGs before prescribing psychotropic medication. A semi-systematic literature review was conducted using PubMed. The terms 'Brugada', 'Brugada Syndrome' AND 'psychotropic' 'antipsychotic' 'antidepressant' 'mood stabilisers' 'clozapine' 'Tricyclic Antidepressants' 'Lithium' were searched. From a search that delivered over 200 articles, 82 articles were included. Those that included details around causative medication, doses of medication and where clear timeline on drug cause were included. Where clarification was needed, the manufacturer of the medication was contacted directly. Psychotropic medication can be associated with BrS, Brugada phenocopy or unmasking of BrS, in overdose or in normal doses. Our results include a table summarising a number of psychotropic overdoses that led to BrS unmasking. Routine screening for BrS in patients before prescribing psychotropic medication is a natural extension of the baseline ECG currently routinely done to rule out QTc prolongation. Psychiatrists need to invest in ensuring better skills in interpreting ECGs and work closer with cardiologists in interpreting ECGs.

Recommendations for participation in leisure-time physical activity and competitive sports of patients with arrhythmias and potentially arrhythmogenic conditions. Part 2: ventricular arrhythmias, channelopathies, and implantable defibrillators

This paper belongs to a series of recommendation documents for participation in leisure-time physical activity and competitive sports by the European Association of Preventive Cardiology (EAPC). Together with an accompanying paper on supraventricular arrhythmias, this second text deals specifically with those participants in whom some form of ventricular rhythm disorder is documented, who are diagnosed with an inherited arrhythmogenic condition, and/or who have an implanted pacemaker or cardioverter defibrillator. A companion text on recommendations in athletes with supraventricular arrhythmias is published in the European Journal of Preventive Cardiology. Since both texts focus on arrhythmias, they are the result of a collaboration between EAPC and the European Heart Rhythm Association (EHRA). The documents provide a framework for evaluating eligibility to perform sports, based on three elements, i.e. the prognostic risk of the arrhythmias when performing sports, the symptomatic impact of arrhythmias while performing sports, and the potential progression of underlying structural problems as the result of sports.

J wave syndromes as a cause of malignant cardiac arrhythmias

The J wave syndromes, including the Brugada (BrS) and early repolarization (ERS) syndromes, are characterized by the manifestation of prominent J waves in the electrocardiogram appearing as an ST segment elevation and the development of life-threatening cardiac arrhythmias. BrS and ERS differ with respect to the magnitude and lead location of abnormal J waves and are thought to represent a continuous spectrum of phenotypic expression termed J wave syndromes. Despite over 25 years of intensive research, risk stratification and the approach to therapy of these two inherited cardiac arrhythmia syndromes are still rapidly evolving. Our objective in this review is to provide an integrated synopsis of the clinical characteristics, risk stratifiers, as well as the molecular, ionic, cellular, and genetic mechanisms underlying these two syndromes that have captured the interest and attention of the cardiology community over the past two decades.

Recent advances in the treatment of Brugada syndrome

INTRODUCTION

Brugada syndrome (BrS) is an inherited cardiac arrhythmia syndrome characterized by ST-segment elevation in right precordial ECG leads and associated with sudden cardiac death in young adults. The ECG manifestations of BrS are often concealed but can be unmasked by sodium channel blockers and fever. Areas covered: Implantation of a cardioverter defibrillator (ICD) is first-line therapy for BrS patients presenting with prior cardiac arrest or documented VT. A pharmacological approach to therapy is recommended in cases of electrical storm, as an adjunct to ICD and as preventative therapy. The goal of pharmacological therapy is to produce an inward shift to counter the genetically-induced outward shift of ion channel current flowing during the early phases of the ventricular epicardial action potential. This is accomplished by augmentation of I_Ca using □□adrenergic agents or phosphodiesterase III inhibitors or via inhibition of I_to. Radiofrequency ablation of the right ventricular outward flow tract epicardium is effective in suppressing arrhythmogenesis in BrS patients experiencing frequent appropriate ICD-shocks. Expert commentary: Understanding of the pathophysiology and approach to therapy of BrS has advanced considerably in recent years, but there remains an urgent need for development of cardio-selective and ion-channel-specific I_to blockers for treatment of BrS.

Comparisons of clinical impacts on individuals with Brugada electrocardiographic patterns defined by ISHNE criteria or EHRA/HRS/APHRS criteria: a nationwide community-based study

INTRODUCTION

Identifying Brugada electrocardiographic pattern (BrP) early is crucial to prevent sudden cardiac death. Two different diagnostic criteria proposed by International Society for Holter and Noninvasive Electrocardiography (ISHNE) and Heart Rhythm Society/European Heart Rhythm Association/Asia-Pacific Heart Rhythm Society (HRS/EHRA/APHRS) were widely used in clinical practice. The difference in prevalence and prognosis of BrP by applying the two different criteria was never studied before.

METHODS

This study was prospectively conducted in a nationwide large-scale stratified random sampling community-based cohort (HALST) from Han Chinese population in Taiwan from December 2008 to December 2012. We compared the prevalence and prognosis of BrP defined by the two diagnostic criteria.

RESULTS

A total of 5214 adults were enrolled (2530 men) with mean age of 69.3 years. Four had spontaneous type 1 BrP (0.077%). By the HRS/EHRA/APHRS criteria, 68 individuals have type 2 BrP (1.30%) and 101 have type 3 BrP (1.94%) whereas by the ISHNE criteria, 46 individuals exhibited type 2 BrP (0.88%). When applying the ISHNE criteria, the number of individuals with BrP decreased by 71%. However, all-cause mortality and cardiovascular mortality were not different between individuals with or without BrP, irrespective of the criteria used.

CONCLUSIONS

The two different criteria may impact the diagnostic yield of individuals with BrP, but do not affect the prognosis of the individuals with BrP. Key messages Comparing with the use of HRS/EHRA/APHRS criteria, the number of individuals with Brugada ECG patterns was decreased by 71% when applying the ISHNE criteria. The prognosis of individuals with Brugada ECG patterns defined by 2012 ISHNE or 2013 HRS/EHRA/APHRS criteria were not different.

Prevalence of spontaneous Brugada ECG pattern recorded at standard intercostal leads: A meta-analysis

OBJECTIVE

Typical Brugada ECG pattern is the keystone in the diagnosis of Brugada syndrome. However, the exact prevalence remains unclear, especially in Asia. The present study was designed to systematically evaluate the prevalence of spontaneous Brugada ECG pattern recorded at standard leads.

METHODS

We searched the Medline, Embase and Chinese National Knowledge Infrastructure (CNKI) for studies of the prevalence of Brugada ECG pattern, published between Jan 1, 2003, and September 1, 2016. Pooled prevalence of type 1 and type 2-3 Brugada ECG pattern were estimated in a random-effects model, and group prevalence data by the characteristic of studies. Meta-regression analyses were performed to explore the potential sources of heterogeneity, and sensitivity analyses were conducted to assess the effect of each study on the overall prevalence.

RESULTS

Thirty-nine eligible studies involving 558,689 subjects were identified. Pooled prevalence of type 1 and 2-3 Brugada ECG pattern was 0.03% (95%CI, 0.01%-0.06%), and 0.42% (95%CI, 0.28%-0.59%), respectively. Regions, sample size, year of publication were the main source of heterogeneity. The prevalence of type 1 Brugada ECG pattern was higher in male, Asia, adult, patient, and fever subjects; but the relation between fever and type 2-3 Brugada ECG pattern was not significant. Sensitivity analysis showed that each study did not lonely affect the prevalence of type 1 and type 2-3 Brugada ECG pattern.

CONCLUSION

Brugada ECG pattern is not rare, especially preponderant in adult Asian males, and fever subjects. Clinical screening and further examination of Brugada syndrome in potential population need to be highlighted.

[Sudden cardiac death : Epidemiology, pathophysiology and risk stratification]

Sudden cardiac death (SCD) remains a major public health burden despite revolutionary progress in the last three decades in the treatment of ventricular tachyarrhythmia with the use of implantable cardioverter defibrillator (ICD) therapy. Survivors of sudden cardiac arrest are at high risk for recurrent tachyarrhythmia events. Early recognition of low left ventricular ejection fractions (≤35%) as a strong predictor of mortality and the causal association between ventricular tachyarrhythmia and SCD has led to a significant development of not only pharmacological antiarrhythmic therapy but also device-based prevention of SCD. The ICD therapy is nowadays routinely used for primary prevention of SCD in patients with significant structural cardiomyopathy and primary electrical arrhythmia syndromes, which are associated with high a risk and secondary prevention in survivors of sudden cardiac arrest. Additionally, effective approaches exist to significantly reduce the recurrence rate of ventricular tachyarrhythmia of various origins by complex electrophysiological endocardial and epicardial catheter ablation procedures.

Brugada syndrome: A general cardiologist's perspective

Brugada syndrome (BrS) is one of the commonest inherited primary arrhythmia syndromes typically presenting with arrhythmic syncope or sudden cardiac death (SCD) due to polymorphic ventricular tachycardia and ventricular fibrillation precipitated by vagotonia or fever in apparently healthy adults, less frequently in children. The prevalence of the syndrome (0.01%-0.3%) varies among regions and ethnicities, being the highest in Southeast Asia. BrS is diagnosed by the "coved type" ST-segment elevation≥2mm followed by a negative T-wave in ≥1 of the right precordial leads V₁-V₂. The typical electrocardiogram in BrS is often concealed by fluctuations between normal, non-diagnostic and diagnostic ST-segment pattern in the same patient, thus hindering the diagnosis. Presently, the majority of BrS patients is incidentally diagnosed, and may remain asymptomatic for their lifetime. However, BrS is responsible for 4-12% of all SCDs and for ~20% of SCDs in patients with structurally normal hearts. Arrhythmic risk is the highest in SCD survivors and in patients with spontaneous BrS electrocardiogram and arrhythmic syncope, but risk stratification for SCD in asymptomatic subjects has not yet been fully defined. Recent achievements have expanded our understanding of the genetics and electrophysiological mechanisms underlying BrS, while radiofrequency catheter ablation may be an effective new approach to treat ventricular tachyarrhythmias in BrS patients with arrhythmic storms. The present review summarizes our contemporary understanding and recent advances in the inheritance, pathophysiology, clinical assessment and treatment of BrS patients.

Brugada syndrome: a fatal disease with complex genetic etiologies - still a long way to go

Brugada syndrome (BrS) is an arrhythmogenic disorder which was first described in 1992. This disease is a channelopathy characterized by ST-segment elevations in the right precordial leads and is susceptible to sudden death. BrS is a fatal disease with gender and age preferences. It occurs mainly in young male subjects with a structurally normal heart and silently progresses to sudden death with no significant symptoms. The prevalence of BrS has been reported in the ranges of 5–20 per 10 000 people. The disease is more prevalent in Asia. Nowadays, numerous variations in 23 genes have been linked to BrS since the first gene SCN5A has been associated with BrS in 1998. Not only can clinical specialists apply these discoveries in risk assessment, diagnosis and personal medicine, but also forensic pathologists can make full use of these variations to conduct death cause identification. However, despite the progress in genetics, these associated genes can only account for approximately 35% of the BrS cases while the etiology of the remaining BrS cases is still unexplained. In this review, we discussed the prevalence, the genes associated with BrS and the application of molecular autopsy in forensic pathology. We also summarized the present obstacles, and provided a new insight into the genetic basis of BrS.

Prevalence of Electrocardiographic Patterns Associated With Sudden Cardiac Death in the Spanish Population Aged 40 Years or Older. Results of the OFRECE Study

INTRODUCTION AND OBJECTIVES

Some electrocardiographic patterns are associated with an increased risk of sudden cardiac death due to ventricular arrhythmias. There is no information on the prevalence of these patterns in the general population in Spain. The objective of this study was to analyze the prevalence of these patterns and associated clinical and epidemiological factors.

METHODS

This subanalysis of the OFRECE study selected a representative sample of the Spanish population aged ≥ 40 years. We studied the presence or absence of electrocardiographic patterns of Brugada syndrome and QT interval abnormalities. Clinical data and electrocardiograms were available in all participants. Electrocardiograms were evaluated by 2 cardiologists and a third cardiologist was consulted if there was disagreement in the diagnosis. We calculated the weighted prevalence and clinical factors associated with the presence of Brugada-type patterns or QT segment abnormalities.

RESULTS

Overall, 8343 individuals were evaluated (59.2 years, 52.4% female). There were 12 Brugada cases (type 1, 2 cases; type 2, 10 cases; weighted prevalence, 0.13%). For corrected QT (QTc) analysis, we excluded participants with left bundle branch block or without sinus rhythm. Weighted prevalences were as follows: short QTc (< 340ms) 0.18%, borderline QTc (441-469ms) 8.33%, long QTc (≥ 470ms criterion) 1.01% and long QTc (≥ 480 criterion) 0.42%.

CONCLUSIONS

A total of 0.6% to 1.1% of the Spanish population aged ≥ 40 years has an electrocardiographic pattern associated with a higher risk of sudden death (Brugada syndrome, long QT, or short QT).

A meta-analytic review of prevalence for Brugada ECG patterns and the risk for death

BACKGROUND

The prevalence of Brugada ECG pattern (BrEP) is different in different regions, and its mean prevalence over the world is unknown. The risk of people with BrEP for death remains unknown. We performed a meta-analysis to determine the prevalence of BrEP and risk ratio (RR) for death.

METHODS

Relevant studies published between July 1, 2000 and August 20, 2016, which contain prevalence and RR for all-cause death and cardiac death, were included. The prevalence and RR are analyzed using meta-analysis.

RESULTS

We finally retrieved 24 studies of the prevalence for BrEP and 5 studies of the RR for all-cause death and cardiac death. The worldwide mean prevalence of BrEP is 0.4%, with highest in Asia (0.9%) and lowest in North America (0.2%). Additionally, the mean prevalence in male is 0.9%, whereas it is 0.1% in female. The RR of BrEP for all-cause death is 0.78 (95% confidence interval 0.45-1.37), and for cardiac death it is 0.92 (95% confidence interval 0.23-3.66).

CONCLUSION

The prevalence of BrEP is about 0.4% around the world with different prevalence in region and sex. Our study shows that BrEP may not be taken as a predictor of all-cause death and cardiac death.

Clinical evaluation of unselected cardiac arrest survivors in a tertiary center over a 1-year period (the LAZARUZ study)

OBJECTIVES

When the cause of an aborted cardiac arrest is unclear the initiation of therapy, counseling and family screening is challenging.

METHODS

We included 43 unselected, prospectively identified cardiac arrest survivors with or without a diagnosis. Family history for cardiac disease and supplemental electrocardiograms were evaluated for additional diagnostic information.

RESULTS

43 cardiac arrest survivors were included, 34 (79%) were male and the average age was 48years (range 23-64, SD 13.0). The most common etiologies identified in cardiac arrest survivors were ischemic heart disease (33%), cardiomyopathies (14%), miscellaneous (e.g. drug induced arrhythmias, coronary spasms) (12%) and channelopathies (5%). Family history of cardiac disease - even inheritable conditions - was not indicative of etiology in cardiac arrest survivors. Supplemental ECGs were abnormal in 10 of 43 patients; in the majority of these patients (7) no conclusive diagnosis was reached.

CONCLUSIONS

In this study 16/43 (37%) of unselected, prospectively included cardiac arrest survivors remained without a diagnosis despite exhaustive investigations. We may extract additional diagnostic information from simple maneuvers during the recording of the electrocardiogram. We suggest that these ECG derived clues be investigated in future studies including genetic test results and data from relatives.

Brugada Syndrome: Clinical, Genetic, Molecular, Cellular, and Ionic Aspects

Brugada syndrome (BrS) is an inherited cardiac arrhythmia syndrome first described as a new clinical entity in 1992. Electrocardiographically characterized by distinct coved type ST segment elevation in the right-precordial leads, the syndrome is associated with a high risk for sudden cardiac death in young adults, and less frequently in infants and children. The electrocardiographic manifestations of BrS are often concealed and may be unmasked or aggravated by sodium channel blockers, a febrile state, vagotonic agents, as well as by tricyclic and tetracyclic antidepressants. An implantable cardioverter defibrillator is the most widely accepted approach to therapy. Pharmacologic therapy is designed to produce an inward shift in the balance of currents active during the early phases of the right ventricular action potential (AP) and can be used to abort electrical storms or as an adjunct or alternative to device therapy when use of an implantable cardioverter defibrillator is not possible. Isoproterenol, cilostazol, and milrinone boost calcium channel current and drugs like quinidine, bepridil, and the Chinese herb extract Wenxin Keli inhibit the transient outward current, acting to diminish the AP notch and thus to suppress the substrate and trigger for ventricular tachycardia or fibrillation. Radiofrequency ablation of the right ventricular outflow tract epicardium of patients with BrS has recently been shown to reduce arrhythmia vulnerability and the electrocardiographic manifestation of the disease, presumably by destroying the cells with more prominent AP notch. This review provides an overview of the clinical, genetic, molecular, and cellular aspects of BrS as well as the approach to therapy.

The spectrum of epidemiology underlying sudden cardiac death

Sudden cardiac death (SCD) from cardiac arrest is a major international public health problem accounting for an estimated 15%-20% of all deaths. Although resuscitation rates are generally improving throughout the world, the majority of individuals who experience a sudden cardiac arrest will not survive. SCD most often develops in older adults with acquired structural heart disease, but it also rarely occurs in the young, where it is more commonly because of inherited disorders. Coronary heart disease is known to be the most common pathology underlying SCD, followed by cardiomyopathies, inherited arrhythmia syndromes, and valvular heart disease. During the past 3 decades, declines in SCD rates have not been as steep as for other causes of coronary heart disease deaths, and there is a growing fraction of SCDs not due to coronary heart disease and ventricular arrhythmias, particularly among certain subsets of the population. The growing heterogeneity of the pathologies and mechanisms underlying SCD present major challenges for SCD prevention, which are magnified further by a frequent lack of recognition of the underlying cardiac condition before death. Multifaceted preventative approaches, which address risk factors in seemingly low-risk and known high-risk populations, will be required to decrease the burden of SCD. In this Compendium, we review the wide-ranging spectrum of epidemiology underlying SCD within both the general population and in high-risk subsets with established cardiac disease placing an emphasis on recent global trends, remaining uncertainties, and potential targeted preventive strategies.

Long-term prognosis of patients with Brugada syndrome and an implanted cardioverter-defibrillator

INTRODUCTION

Risk stratification of Brugada syndrome (BrS) remains controversial and recommendations for an implantable cardioverter-defibrillator (ICD) are not well established. The objective of this study was to assess the long-term prognosis of BrS patients with an ICD.

METHODS AND RESULTS

Of 55 consecutive patients with BrS assessed between April 2002 and October 2012, 36 (mean age 41.7 ± 13.8 years; 81.8% male) underwent ICD implantation. Nineteen (52.8%) were asymptomatic, 11 (30.6%) had previous history of syncope (arrhythmic cause suspected in eight) and six (16.7%) had aborted sudden cardiac death (SCD). Spontaneous type 1 electrocardiographic (ECG) pattern was present in 25 (69.4%) patients and electrophysiological study (EPS), performed in 26 (72.2%), was positive in 22 (84.6%). During a mean follow-up of 74 ± 40 months (>5 years in 72% of cases), seven (19.4%) patients had appropriate shocks (annual event rate 2.8%). These patients most frequently had aborted SCD (54.1% vs. 6.9%; p=0.008) and nonsustained ventricular tachycardia (57.1% vs. 10.3%; p=0.016) during follow-up. Spontaneous type 1 ECG pattern, syncope and positive EPS were not significantly associated with appropriate shocks. Multivariate analysis revealed that aborted SCD was an independent predictor of appropriate shocks (HR 8.07, 95% CI 1.58-41.2; p=0.012). ROC curve analysis demonstrated that aborted SCD had moderate discriminatory power to predict appropriate shocks (AUC 0.751), with sensitivity of 57% and specificity of 93%. In terms of ICD-related complications, eight (22.2%) patients had inappropriate shocks during the follow-up period, mainly due to sinus tachycardia (five patients); one patient had lead infection and another had a lead fracture.

CONCLUSION

In this population of BrS patients with ICD, the long-term rate of appropriate shocks was 2.8%/year. Aborted SCD was associated with a higher risk of appropriate shocks, whereas syncope and spontaneous type I ECG pattern did not predict this event.

Arrhythmogenesis in Brugada syndrome: impact and constrains of current concepts

Brugada syndrome (BrS), an inherited arrhythmogenic disease first described in 1992, is characterized by ST segment elevations on the electrocardiogram in the right precordium and by a high occurrence of arrhythmias including the life-threatening ventricular tachycardia/fibrillation. Knowledge of the underlying mechanisms of formation of arrhythmogenic substrate in BrS is essential, namely for the risk stratification of BrS patients and their therapy which is still restrained almost exclusively to the implantation of cardioverter/defibrillator. In spite of many crucial findings in this field published within recent years, the final consistent view has not been established so far. Hence, BrS described 20 years ago remains an actual topic of both clinical and experimental studies. This review presents an overview of the current knowledge related to the pathogenesis of BrS arrhythmogenic substrate, namely of the genetic basis of BrS, functional consequences of mutations related to BrS, and arrhythmogenic mechanisms in BrS.

Specificity of elevated intercostal space ECG recording for the type 1 Brugada ECG pattern

BACKGROUND

Right precordial (V1-3) elevated electrode placement ECG (EEP-ECG) is often used in the diagnosis of Brugada syndrome (BrS). However, the specificity of this has only been studied in smaller studies in Asian populations. We aimed to study this in a larger European population.

METHODS

Two different populations consisting of healthy subjects were used. A total of 340 subjects were included, 80% were men, the median age was 43 year (interquartile range: 31-51) and all were of European ethnicity.

RESULTS

No type 1 ECG patterns were identified but 16 (4.7%) subjects with a type 2 ECG and 32 (9.4%) subjects with a type 3 ECG were identified in any lead placement. In total 43 (13%) subjects had any BrS ECG pattern in any lead placement. The specificity was 100% (one-sided 97.5% CI: 99%) for the use of EEP-ECG to uncover type 1 pattern. For type 2 pattern the specificity was 95% (95% CI: 92-97%) and for type 3 pattern 91% (95% CI: 88-94%).

CONCLUSIONS

Elevated electrode placement ECG in the diagnosis of BrS seems to have a very high specificity with regards to the finding of a type 1 ECG pattern in a European population; conversely a finding of a type 2 or 3 pattern is of a significantly lower specificity and should perhaps be disregarded.

Prevalence of electrocardiographic abnormalities in an unselected young male multi-ethnic South-East Asian population undergoing pre-participation cardiovascular screening: results of the Singapore Armed Forces Electrocardiogram and Echocardiogram screening protocol

AIMS

Resting 12-lead electrocardiograms (ECGs) have been employed in the pre-participation evaluation of young asymptomatic subjects to detect pre-existing heart diseases. Although the incorporation of routine ECG in pre-participation screening remains controversial, there is increasing evidence that cardiomyopathies and ion channelopathies have ECG changes as the initial manifestation. The causes of sudden cardiac death in young people show significant geographical variation. We aim to determine the prevalence and spectrum of ECG abnormalities in a young male South-East Asian population.

METHODS AND RESULTS

The Singapore Armed Forces Electrocardiogram and Echocardiogram (SAFE) protocol is an ECG-based pre-participation cardiac screening programme modelled after the Italian system. From October 2008 to May 2009, a total of 18 476 young male conscripts (mean age 19.5 years old, range 16-27) underwent mandatory pre-enlistment medical screening at a single medical facility. Subjects with abnormal ECG findings were classified into two groups: Group A had ECG changes that fulfilled a pre-specified checklist to screen for hypertrophic cardiomyopathy and were referred for transthoracic echocardiogram; Group B had other ECG abnormalities [such as Brugada pattern, Wolff-Parkinson-White (WPW) pattern, long QTc] and were referred for secondary screening at a tertiary institution. Of the 18 476 subjects screened, 7.0% (n= 1285) had ECG abnormalities. Of note, 19 (0.10%) had Brugada pattern, 25 (0.14%) had WPW pattern, and 31 (0.17%) had prolonged QT interval on ECG. The prevalence of ECG abnormalities was significantly higher in Chinese than in South Asians (7.2 vs. 5.7%, P= 0.003).

CONCLUSION

The prevalence of ECG abnormalities in a young, South-East Asian male population was 7.0%. There were significant ethnic differences, with ECG abnormalities more prevalent in Chinese than in South Asians (7.2 vs. 5.7%, P= 0.003). The inclusion of universal ECG, in addition to history and physical examination, may increase the sensitivity of a cardiovascular screening programme. Knowledge of the spectrum and prevalence of ECG abnormalities and disease conditions would be pivotal in designing customized screening programmes.